The present invention relates to vibration dampers for dampening vibrations in a vehicle seat.
Numerous vehicle seat suspensions are known, including those having air bag or air spring suspensions for resiliently supporting a seat in a selected position. In such suspension systems, pressurized air is delivered to or exhausted from the air bag to adjust the elevation of the seat. The use of an air bag permits upward and downward vibrations of the seat. To counteract these vibrations, shock-absorbing cylinders have been used to dampen the seat vibrations.
In one known approach, as the elevation of the seat suspension is changed by inflating or deflating the air bag, the shock absorbing cylinder has a piston supporting rod which extends or retracts, depending upon the direction in which the seat elevation is changed. In this approach, the shock absorbing cylinder must be capable of extension and retraction throughout the entire range of seat elevation adjustment. In addition, these seat suspension systems are understood to use shock absorbing cylinders with pistons that apply a constant dampening force over the full stroke of the piston. If the dampening force were non-constant in such systems, problems would ensue. For example, in such systems a non-constant dampening force would mean that the ride provided by the seat would vary depending upon the seat elevation.
U.S. Pat. No. 3,951,373 illustrates one form of seat suspension utilizing a shock absorbing cylinder and an air bag or air spring. In this construction, the shock absorber is understood to have a stroke which is capable of extending and retracting throughout the full range of seat height adjustment. However, in this construction, a hand knob may be operated to adjust the throw of a shaft to thereby change the effective length of the shock absorber.
Although numerous seat suspension systems are known, a need nevertheless exists for an improved vibration damper for a seat suspension system, with new and non-obvious differences from vibration dampers used in known systems.